"ORA-00845: MEMORY_TARGET not supported on this system" while Starting Oracle DB

Oracle Database Start-up Issue in Linux
#sqlplus /nolog
SQL> connect / as sysdba
Connected to an idle instance.
SQL> startup;
ORA-00845: MEMORY_TARGET not supported on this system

Cause:
This Error is due to the disk size of  tmpfs( /dev/shm ) is lesser than the memory_target space allocated to the oracel DB in spfile.ora

Resolution:
The value of memory target can be obtain from the following location
$ORACLE_HOME/dbs/spfile<SID>.ora
Make tmpfs  ( /dev/shm )  disk size more than memory_target by editing /etc/fstab  by editing the following :
tmpfs                   /dev/shm                tmpfs   defaults,size=4G        0 0
(mentioned size according to your environment)
#mount -o remount /dev/shm
To make tmpfs static on boot, above line should be entered in /etc/rc.local
SQL> connect / as sysdba
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 4192272384 bytes
Fixed Size                  2182384 bytes
Variable Size            3338666768 bytes
Database Buffers          838860800 bytes
Redo Buffers               12562432 bytes
Database mounted
Database Started